The present invention relates to an automated biological apparatus and, more particularly to a method and apparatus for rinsing a biological sample on a slide.
Processing of biological samples, such as immunohistochemical staining, typically occurs by placing the biological sample on a standard slide. The slides are placed in a staining machine, such as the machine disclosed in U.S. application Ser. No. 08/995,052 filed on Dec. 19, 1997, which is hereby incorporated by reference in its entirety. An important feature in the processing is the control of the amount of liquid on the slide. During processing, a specific, predetermined amount of liquid on a biological sample is typically desired. However, prior art methods of rinsing or removing the amount of liquid on the slide are inaccurate in the control of the amount of fluid on the slide, have the possibility of disrupting the sample on the slide and/or are complicated in their mechanics. One such method includes sending a stream of liquid from one end of the slide to the other end of the slide via a volume controlling device (i.e., “pushing” the liquid off of the slide). Specifically, the volume controlling device sends streams or jets of liquid onto the section of the slide proximate to the volume controlling device so that the rinse liquid passes over the portion of the slide where the biological sample is placed and off of the distal end. In this manner, the stream of liquid “pushes” the liquid off of the slide. This method, however, may disrupt the biological sample due to the passing of fluid over the biological sample.
Another method to control the amount of fluid on a slide is by rotating the slide so that the liquid runs off by gravity. This method uses a slide holder that allows the rotation of the slide and an air cylinder that pushes a tab on the holder to make it rotate and “tip” the slide over, thus permitting the aqueous to drain off. However, the mechanics required for rotation of the slide may be complicated. Accordingly, it is desirable to have an improved method and apparatus to control the amount of fluid on the top of a slide.